DE3506808A1 - METHOD FOR TREATING KAOLINITE BY FLOTATION - Google Patents

Abstract

Process for the selective separation of kaolinite and feldspar by flotation in aqueous pulp, wherein flotation is carried out at the pH-value of the pulp which is naturally obtained during suspension of the mixture of minerals in water using water-soluble salts with trivalent metal ions as activators and depressors, in the presence of cationic and/or anionic surfactants as collectors, and optionally in the presence of other standard flotation aids.

Description

Process for processing kaolinite
by flotation

The invention relates to a method for processing kaolinite by flotation, in particular a method separated by the kaolin and feldspar in the finest grain range and both minerals in pure form in high yields can be obtained.

Kaolinite is a naturally occurring industrial mineral for its diverse and varied uses as a filler in the paper and ceramics industry, in the plastics industry, in production There is a great and increasing demand for paints, varnishes, rubber and cables. Kaolinite is created by exogenous (weather, groundwater) and endogenous (hydrothermal hot solutions, deep vapors) influences predominantly acidic pH values from feldspar (Ulimann's Encyclopedia of Technical Chemistry, Volume 13, page 509 (1977)). High quality demands on the kaolinite product in terms of purity are all the more difficult to meet the higher in existing and newly created.

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closed kaolinite deposits which are not yet kaolinized feldspar and quartz. Kaolinite must be selectively separated from these accompanying rocks.

05

The processing of the raw kaolin, which in addition to the main mineral kaolinite usually also includes feldspar, quartz and Containing various iron and titanium minerals is mostly done by wet processes in which the kaolinite Raw earth is slurried in water. The following separation process is a separation of the various Mineral proportions based on grain size and specific weight. Since those accompanying the kaolinite Minerals quartz and feldspar are generally coarser ("antiparallel grain distribution"), to separate the coarser quartz and feldspar up to grain sizes of 20 μπα from kaolinite satisfactorily (see M.

Clement and H. M. Tröndle; Erzmetall 2_2, H. 3, 131

(1969)).

In view of the fact that feldspar is also a popular raw material in the ceramics industry, when separating kaolinite and feldspar from raw kaolin, the aim is to obtain, in addition to the purest possible kaolinite, a feldspar product that meets high standards for industrial use in glass and Ceramic industry is enough. It is known that mechanical separation processes are used in aqueous turbidity for this purpose. However, the effectiveness of such separation processes reaches a limit when the grain sizes of kaolinite and feldspar in the finest grain range are very close to one another, since the specific gravity of the two minerals (approx. 2.58 g / cm ³ ) is practical

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is equal to. In such a case, the requirement for high purity of both end products, kaolinite and feldspar, is associated with a loss in the inseparable grain classes (finest grain range), which is of considerable economic importance. The separation of kaolinite and feldspar in aqueous turbidity is explained in detail in BM Coope, Industrial Minerals, 1979 , 33 to 49 and HH Murray, Int. J. of Mineral

Processing T_, 263 (1980). 10

Flotation processes are used in mineral purification practice to remove heavy metal oxides, e.g. To remove oxides of iron and titanium from kaolinite and thereby improve the whiteness of the product.

There are also separate processes for separating kaolinite from quartz on the one hand and feldspar from quartz on the other hand by flotation of the minerals in the presence of an amine as a collector from HM Tröndle, M. Clement and B. Becher, Interceram JL9, 185 and 268 (1970) according to Chemical Abstracts JA ' 102589 u (1972) known. Hydrochlorides and hydroacetates of long-chain aliphatic amines were used as collectors in acidic turbidity.

² ^ Flotation experiments with kaolin-quartz or feldspar-quartz mixtures are also described in HM Tröndle, M. Clement and B. Brehler, Keramische Zeitschrift 2X_, 423 and 489 (1969), corresponding to Chemical Abstracts 72 , 102251 m (1970) described. Hydrofluoric and hydrochloric acid aqueous pulp were used with long-chain aliphatic amines as collectors to separate the respective kaolinite or feldspar minerals from quartz. In the process of separating the

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Quartz kaolinite has also been found to cause a sharp decrease in kaolinite yield with alkaline pH values of the aqueous slurry is due to the fact that the undissociated amine molecules, according to of the following equation (1) arise, no longer adsorb on the negatively charged kaolin surface and thus prevent the kaolinite portion of the sludge from being discharged with the aid of the ammonium salt.

R-NH ₃ ⁺ + OH ~ <= * R-NH ₂ + H ₃ O (1)

For the processing of kaolinite and feldspar-containing aqueous pulp, the area of the finest grain size of both mineral particles is of particular interest; a separation of the two minerals in this grain range on an industrial scale has not yet been possible. In practice, however, this area plays an outstanding role as mineral mixtures with a particle size distribution of 90% less than 30 μm for kaolinite and 10% less than 30 μm for feldspar arise in the washing out of the deposits containing kaolinite and feldspar. Kaolins suitable for use in ceramics even have a fine grain fraction (less than 2 μm) of 50% and more. In the range of these grain sizes, selective flotation in aqueous sludge causes major problems. The direct flotation for the separation of kaolinite and feldspar in this grain range has not yet been described.

It is known that polyvalent cations are present on the surfaces of the mineral particles in the aqueous turbidity are slurried, adsorbed and the FIo-

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can influence the animal ability of these mineral particles within wide limits (B. Dobias, 6. Internationaler Congress for Surface-Active Substances, Zurich 1972, page 563 (1973)). Also are polyvalent cations able to work with the collector surfactant with the formation of complex compounds or poorly soluble precipitates to react and in this way the surfactant the desired adsorption process on the surface of the To withdraw mineral particles. Experience has shown that the flotation yield decreases, if not increased quantities of the collector surfactant can be used.

One and the same polyvalent cation can - depending on the composition of the material to be processed by flotation Systems - for the selected collector (surfactant) both activating and deactivating effect during flotation of mineral particles show. When which of the two properties dominates is only empirical determine. As a rule, these effects work, their mechanisms of action not fully in detail are known to be more disruptive than beneficial in the flotation process itself. The undesirable effect of polyvalent Preventing cations in the flotation process is therefore a special problem in processing

25 of the respective minerals.

The activating or deactivating ("pressing") effect of polyvalent metal cations on silicate Minerals is partly known from the literature. It is reported in Chemical Abstracts 6jB, 116 041a (1968), that aluminum, iron and calcium ions have an activating effect in the flotation of quartz,

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Have feldspar and sillimanite. This increases the concentration of iron (III) and aluminum (III) salts If values are increased above 300 mg per liter, this occurs more clearly in acidic and alkaline pH-value ranges Decrease in the activating effect of silicate flotation.

The use of cationic collectors in acidic media in the flotation separation of quartz-feldspar sands in the presence of copper (II), calcium, iron (III) and aluminum (III) ions is described in Chemical Abstracts 71 , 5014h (1969) described. In media with strong sulfuric acid or hydrochloric acid, the cations mentioned have an activating effect on feldspar and pressure on quartz.

Chemical Abstracts _7_i ' ¹⁴⁷ 840p (1973) describes the separation of feldspar from accompanying materials by flotation in the presence of aliphatic amines or petroleum sulfonates in strong sulfuric acid solutions. _{SiO 2} , A1, O_ and Fe_O_ are added to the aqueous pulp as activators, with the output of feldspar from the pulp increasing as the concentration of collectors increases.

in Neue Bergbautechnik 9_, 349 (1979), corresponding to Chemical Abstracts 9_2, 150 570 (1980) it is described that aluminum trichloride has an activating effect on feldspar and a depressing effect in the aqueous flotation of feldspar-quartz mixtures in the presence of long-chain aliphatic amines Exercises quartz in the turbidity. However, the problem of the separation of kaolinite and feldspar in aqueous sludge is not addressed in any of the cited references.

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'J ·

It has now been found that it can be used to separate kaolinite and feldspar by flotation is by no means necessary, the aqueous turbidity with the help of hydrohalic acids or to adjust sulfuric acid to strongly acidic pH values. A selective separation of kaolinite Rather, feldspar also works at a natural pH value, which increases when the minerals are slurried adjusts to a value of 5 to 8 in water. It has also been found that in the natural pH range the addition of trivalent metal ions, for example

3+ 3+
wise Al or Fe, in the form of corresponding salts, significantly improves the selectivity in the flotation separation of kaolinite and feldspar in the finest grain range. It has also been found that when the aqueous slurry is adjusted to natural pH values and trivalent metal ions are used, flotation with anionic surfactants as collectors is advantageous over cationic flotation.

The invention therefore relates to a method for the selective separation of kaolinite and feldspar by flotation in aqueous slurry, which is characterized in that the flotation is carried out at a pH value of the slurry, which occurs naturally when the mineral mixture is slurried in water, using of water-soluble salts with trivalent metal ions as activators and depressors and in the presence cationic or anionic surfactants as collectors and, if necessary, with the addition of other, Performs in the flotation of conventional auxiliaries.

The pH value at which the process is carried out according to the invention is generally in the range between 5 and 8. This pH value is then obtained
35

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when the mineral mixtures broken down in solid form are suspended in tap water or fully demineralized water or the mineral mixture under high pressure with water jets from the rock is washed out and brought to light. The addition of large amounts of activating acids, for example Hydrohalic acid or sulfuric acid, for adjustment a strongly acidic pH value, as it is from the prior art in such flotation processes It was imperative to set it in order to achieve an effective and selective separation of kaolinite and Feldspar is no longer required according to the invention.

According to the invention, the aqueous slurries also become trivalent salts as activators or depressors Metal ions added. Salts or poly salts are used here of aluminum and ferric salts are used.

In practice, the sulfuric acid salts of trivalent metals are used with advantage. The concentration the salt is in the range from 50 to

2000 g / t, preferably 100 to 1000 g / t, based on

the anhydrous metal salt.

According to the present invention, aluminum salts are particularly preferred, for example aluminum sulfate, used. It has been found that the Al (III) ion in aqueous turbidity at pH values in the range from 5 to 8 activating on kaolinite and deactivating, i.e. pressing, on feldspar. By adding aluminum salts to the aqueous slurry, concentrates with a higher concentration are obtained during flotation Kaolinite concentration obtained. At the same time, the output of kaolinite is increased, so that as flotation residue Feldspar is also obtained in a higher purity.

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As a collector in the method according to the invention cationic or anionic surfactants can be used. For this purpose, compounds are selected as cationic surfactants the group of monoalkyltrimethylammonium compounds, dialkyldimethylammonium compounds, alkylarylammonium compounds, Alkylamines, hydroxylamines and / or hydroxyalkylamine polyglycol ethers are used, the compounds mentioned preferably contain alkyl groups with 12 to 18 carbon atoms. As aryl residues,

10 gives phenyl and / or benzyl radicals in question.

The use of aluminum ions in the separation of kaolinite and feldspar achieved by flotation is made possible however, in particular a procedure below Addition of anionic surfactants as a collector. The flotation with anionic collectors has surprisingly to the extent that it is particularly advantageous compared to flotation with cationic surfactants, as Heavy mineral fractions present in the ore can be separated from kaolinite before flotation, which leads to a higher degree of whiteness of the kaolinite concentrate and a likewise improved quality of the feldspar residue leads. In addition, the subsequent processing ^ of the kaolinite is facilitated to the extent that it is anionic

Surfactants can be more easily desorbed from the surface of the kaolinite particles than cationic surfactants. In addition, it must be taken into account that, simply because of their environmental behavior, anionic surfactants are used cationic surfactants are preferred.

30th

Preferred anionic surfactants are compounds from the group consisting of fatty acids, alkyl sulfates, alkyl ether sulfates, Alkylbenzenesulfonates, petroleum sulfonates, ester sulfonates, Alkylsu] fosuccinates, alkylsulfosuccinamides, Alkyl phosphates and / or alkyl ether phosphates are used. Particularly preferred are alkylbenzenesulfonates,

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Petroleum sulfonates, fatty alcohol sulfates, ester sulfonates and / or alkyl sulfosuccinates with those mentioned above Chain lengths of the alkyl radicals use.

According to the method of the present invention it is also possible to use mixtures of cationic and anionic Surfactants with nonionic additives, for example fatty alcohol, alkyl polyglycol ethers and / or alkylphenol polyglycol ethers, to use.

10

The concentration of surfactants that are used as collectors according to the invention is in the range from 50 to 2000 g / t, preferably 100 to 1000 g / t.

According to the invention, for the separation of kaolinite and feldspar brought about by flotation, the aqueous Cloudy other auxiliaries known to be used in flotation can be added. As such auxiliaries are, for example, foaming agents on the one hand or anti-foaming agents on the other hand, which in contrast however, are not absolutely necessary for methods known from the prior art.

When using the constituents provided according to the invention, kaolinite is used in the mineral mixture and feldspar the first component floats, while feldspar with compared to method from the state the technology of surprisingly high purity is obtained as flotation residue. The respective flotation steps are - depending on the quality requirements of the products - repeated if necessary, whereby A selective separation of the two components is achieved, especially in the finest grain range. According to the invention A further post-cleaning step is sufficient to remove concentrates with a kaolinite content between 93 and get 97%.

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The kaolinite fraction obtained by flotation is worked up in the following process steps. Included the surfactants adsorbed on the surface are desorbed. The preferred anionic ones Surfactants bind the surfactant molecule to the negatively charged surface of the kaolinite particles the ion bridges consisting of trivalent metal ions, so that the anionic surfactants more easily from The surface of the kaolinite can be desorbed as cationic surfactant molecules.

f Another advantage of the method according to the invention

can be seen in the fact that the flotation of kaolinite caused by anionic or cationic surfactants in Presence of trivalent metal ions, preferably aluminum (III) ions, is largely independent of the water hardness and the indifferent content of the turbidity Electrolytes. Bivalent ions, for example calcium or magnesium ions, also improve the selectivity in the flotation of the kaolinite / feldspar mineral mixture, however, this effect only occurs at very high ion concentrations that require the addition the said ions would make the flotation pulp uneconomical.

The selective separation of kaolinite and feldspar brought about by flotation has proven particularly useful of the invention in the range of small grain sizes of the minerals involved, i.e. especially when conventional separation processes presented major problems. Grain sizes are in the range of 30 to 2 µm preferred for the application of the method according to the invention.

Normally, the raw products used for the flotative separation of kaolinite and feldspar are used the quartz content due to a previously

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ongoing separation process extremely low, so that Quartz does not have to be separated. It is, however, also possible to add to the raw product if the quartz content is high the flotation of kaolinite by reactivating it with aluminum ions and adding a collector of feldspar to float to separate quartz. This then takes place practically in accordance with known from the prior art Procedure.

The invention is illustrated in more detail by the following examples.

The flotation tests were carried out in a Humboldt-Wedag laboratory flotation cell of 1 1 or 2 1 content with a kaolinite / feldspar / quartz fraction of one particle size carried out by 90% smaller than 20 µm. This fraction was the intermediate stage in a conventional kaolinite preparation plant been taken.

The selectivity of the flotation, ie the content of kaolinite and feldspar in the concentrate or in the flotation residue, was determined according to the known method via the loss on ignition (DIN 51 081 for testing ceramic raw materials by weight change during annealing (July 1979)).
25th

Examples 1 to 4

The mineral mixture was pretreated for 5 minutes in the flotation cell, in Examples 2 to 4 activating additives (sulfuric acid and / or aluminum sulfate) were added. Then the aqueous solution of a cationic collector Araphen G2D added. The flotation was carried out with an additive a commercially available foamer (Araphen 'G2D15).

The results are shown in Table 1 below.

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CO

Table 1

to

PO

Output and selectivity in the flotation of kaolinite / feldspar

with cationic collector Araphen G2D

example Collector
(g / t) Add
substance etch
concentration
(g / t) Con
Content of
Kaolinite (%) centrate
Application
(%) Flotation residue
Content of
Kaolinite (%) 1 160 - - 73.4 87 10.5 2 260 H ₂ SO ₄ 392 69.6 97 3.7 3 360 Al ₂ (SO ₄ J ₃ 54G 82.5 97 3.3 4th 320 Al ₂ (SO ₄ J ₃
+ H ₂ SO ₄ 274
392 82.2 98 2.2

O.

-O.

Q CD

Q
%

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Result;

While according to Example 1 (without activating additives) the flotation separation performance was extremely poor both with regard to the application of kaolinite in the concentrate and with regard to the kaolinite content was achieved in the flotation residue, the selectivity was increased by the addition of sulfuric acid (Example 2) be improved. The addition of aluminum sulfate significantly improved the selectivity in the flotation, so that concentrates with a high kaolinite content are obtained in a single subsequent cleaning step became.

Examples 5 to 7

Instead of the cationic collector of Examples 1 to 4, cetylpyridinium chloride was used as a cationic collector. The results are as follows Table 2.

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LO

Table 2

ΙΌ O

Output and selectivity in the flotation of kaolinite / feldspar with cationic collector (cetylpyridinium chloride)

I I

3L

Q.

ro
-j

example Collector
(g / t) Add
substance etch
concentration
(g / t) Kon:
Content of
Kaolinite
(%) sentrate
Application
(%) Flotation residue
Content of
Kaolinite
(%) 5 480 H ₂ SO ₄ 392 58.7 98 2.9 6th 440 A1 ₂ (SO ₄ ) ₃ 548 75.8 98 2.5 7th 480 A1 ₂ (SO ₄ ) ₃ 823 86.1 9? 2.9

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Result:

Even when using cetylpyridinium chloride as a cationic collector, there was a significant increase in The selectivity of the separation and an increase in the amount applied were measured when aluminum sulfate was added.

Examples 8-11

In contrast to Examples 1 to 7, the flotation was carried out with an anionic collector (sodium alkylbenzenesulfonate) in the absence (Example 8) or in the presence (Examples 9 to 11) of activating additives carried out. The results are shown in Table 3 below.

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U) O

Table 3

NO

αϊ

Output and selectivity in the flotation of kaolinite / feldspar with anionic collector (sodium alkylbenzenesulfonate)

SL α

example Collector
(g / t) Add
substance etch
concentration
(g / t) Con
Content of
Kaolinite (%) centrate
Application
{%) Lotation rest
Content of
Kaolinite (%) 8th 000 - - 76.0 71 2.4.1 9 680 H ₂ SO ₄ 392 72.9 92 7.5 10 448 ⁺ AlCl ₃ 319 82.8 96 3.9 11 680 ⁺ A1 ₂ (SO ₄ ) ₃
+ H ₂ SO ₄ 273
392 87.0 96 3.4

σ ο

N)

Addition of 140 g / t of an anti-foam agent to regulate foam

in the

"/ ξ OO

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-to-

Result ;

While the use of an anionic collector in the absence of activating additives is relatively poor Produced results with regard to the spread of kaolinite and the residual kaolinite content in the flotation residue, When Al (III) ions were added to the flotation solution, a selective separation of kaolinite and Feldspar achieved, with both the output of kaolinite and the kaolinite content in the flotation residue were significantly cheaper than when using sulfuric acid as an activator.

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Claims (11)

Patent claims 1. Process for the selective separation of kaolinite and Feldspar by flotation in an aqueous slurry, characterized in that the flotation a) at the pH value of the pulp, which naturally occurs when the mineral mixture is slurried in 10 sets water, b) using water-soluble salts with
trivalent metal ions as activators (and depressors and c) in the presence of cationic and / or anionic ones
Surfactants as collectors as well d) possibly with the addition of other, in the FIo- * tation of common auxiliary materials *> performs. 2. The method according to claim 1, characterized in that the flotation at a pH in the range of 5 to 8. 3. The method according to claims 1 and 2, characterized in that that chlorides and / or sulfates of trivalent metal ions are used as water-soluble salts. 4. Process according to Claims 1 to 3, characterized in that the salts of trivalent metal ions are used Aluminum and / or iron (III) salts are used. 5. Process according to Claims 1 to 4, characterized in that aluminum sulfate is used as the activator. Patent application - 3 <Γ - HENKELKGaA D 7 O 2 7 4 ZR-FE / Patents 6. Process according to Claims 1 to 5, characterized in that that one the activator concentration to a range from 50 to 2000 g / t, preferably to 100 to 1000 g / t, based on the anhydrous salt. 05 7. Process according to Claims 1 to 6, characterized in that anionic surfactants are used as collectors. 8. Process according to Claims 1 to 7, characterized in that the collector concentration is reduced to one Range from 50 to 2000 g / t, preferably to a range from 100 to 1000 g / t. _# 9 The method of claims 1 to 8, characterized in that alkyl benzene sulfonates, onate as anionic collectors petroleum sulfonates, fatty alcohol sulfates, Estersulf and / or alkyl sulfosuccinates are used in which the alkyl radicals having 12 to 18 carbon atoms. 20th 30th 10. The method according to claims 1 to 9, characterized in that the flotation pulp is a frother clogs. 11. Process according to Claims 1 to 10, characterized in that an antifoam agent is used for foam regulation clogs. Sd 230/438539 03.04.84